About A Year Ago I Had 3 Of My Front

About a year ago I had 3 of my front teeth knocked out. At the time, I was in braces and so instead of my teeth falling out they instead strung from my gums. About a month after, I had root canals on my front teeth because the nerves were obviously dead and my teeth were infected. In the time period between when they got knocked out and when I had root canals done, I had pain in those teeth whenever I breathed in cold air or ate anything cold. The pain was only in those teeth, but supposedly my nerves were dead. Now, I have severe pain in those teeth whenever I eat or drink anything cold. I was wondering if there was any good explanation for this, because supposedly my nerves are dead so I shouldn't be feeling the cold. I also broke my maxillary bone at the time and the tendons that connect the teeth to the bone were torn as well.